Regular exercise saves lives. The U.S. government advises adults to get 150 to 300 minutes a week of moderate activity, or 75 to 150 minutes of vigorous activity, or a mix of both. What has been less clear is whether doing far more than this helps even more, or could even be harmful.
A large analysis published in Circulation offers a simple answer. The lowest risk of death was seen among people who consistently did about 150 to 300 minutes of vigorous exercise a week, or 300 to 600 minutes of moderate exercise a week. Doing more than that did not add clear extra benefit, and the study found no sign of harm at higher amounts.
What the researchers studied
Scientists followed 116,221 U.S. adults for up to 30 years using detailed surveys repeated many times. Participants came from two famous health cohorts, the Nurses’ Health Study and the Health Professionals Follow‑up Study. Over three decades, the research team recorded 47,596 deaths and compared them with long‑term exercise patterns.
The work was led by Dong Hoon Lee at the Harvard T.H. Chan School of Public Health, with senior investigator Edward L. Giovannucci and colleagues across several institutions, including Brigham and Women’s Hospital. Their goal was practical: to pinpoint how much moderate versus vigorous activity over many years is linked to the biggest drop in mortality.
How much exercise brings the biggest benefit
People who met the basic recommendations did better than those who did none. Meeting the vigorous target was linked to about a 19 percent lower risk of death from any cause, including a 31 percent lower risk from cardiovascular disease. Meeting the moderate target was linked to about a 20 to 21 percent lower risk of death overall.
Going beyond the minimum brought modest extra gains up to a point. Two to four times the recommended amount meant roughly a 21 to 31 percent lower mortality, depending on whether the extra time came from vigorous or moderate activity. Past about 300 minutes a week of vigorous activity or 600 minutes a week of moderate activity, the curve flattened with no clear added benefit.
Does doing more help or harm?
A key concern has been whether very high volumes of intense exercise could backfire for the heart. In this analysis, even people well above four times the recommended amount did not show signs of higher mortality. Benefits simply leveled off, rather than reversing.
Some prior research, including the Copenhagen City Heart Study, suggested a U‑shaped pattern in which too little and too much sport time both track with higher death risk. The new findings help explain why results have differed: long‑term, repeated measures of activity reduce bias from short‑term illness or sporadic bursts of training.
Why this matters for everyday life
For most adults, the takeaway is straightforward. Aim for a weekly routine that lands in the “sweet spot”: about 300 to 600 minutes of moderate activity such as brisk walking, yard work, or easy cycling, or 150 to 300 minutes of vigorous activity such as running, swimming laps, or fast cycling. Mixing the two styles works as well.
For those currently below the guidelines, the biggest payoff comes from adding even a modest amount of activity. The study found that people below 300 minutes a week of moderate exercise gained extra protection by adding some vigorous sessions. This echoes federal guidance to move more and sit less, underscoring that the first steps toward activity yield the most significant returns.
Important limitations
This was an observational study, so it cannot prove cause and effect. People reported their own activity, which can be imprecise, though the repeated surveys over decades reduce common errors and help capture long‑term habits. The groups studied were mostly White health professionals, which may limit how precisely the numbers apply to everyone.
Still, the methods were rigorous. The researchers adjusted for age, smoking, diet quality, sleep, and body weight, and they used a two‑year lag to lessen the chance that undiagnosed illness made people both less active and more likely to die. These steps strengthen confidence in the overall message.
How the findings compare with past research
Earlier pooled analyses found large benefits from meeting the guidelines and suggested a plateau at roughly three to five times the minimum, with no evidence of harm even at very high volumes. The new study agrees on the strong benefits but goes further by teasing apart moderate and vigorous activity over the long haul.
A 2020 systematic review also reported that mortality risk keeps falling well above the basic recommendations, especially for cardiovascular deaths. Together, these lines of evidence support the idea that more movement is usually better, but there is a ceiling where extra hours deliver smaller returns.
The official study has been published in Circulation.
